1. Field of the Invention
The present invention relates to a connector for connecting both a shielded cable and a non-shielded cable.
2. Description of the Related Art
FIGS. 1A and 1B show the structure of an example of the conventional connector of the same type disclosed in Japanese Patent Application Laid Open No. H04-345778 (issued on Dec. 1, 1992). FIG. 1A shows a terminal housing with a shielded cable and a non-shielded cable attached. FIG. 1B shows a connector housing into which the terminal housing is inserted.
A terminal housing 1 includes a shielded terminal 3 for a shielded cable 2 and a non-shielded terminal 5 for a non-shielded cable 4. The shielded terminal 3 is formed by a core-wire terminal 3a covered by an external conductor terminal 3c, with an insulating material 3b placed between them. The core-wire terminal 3a has a contact part 3d, and the base part is secured to and electrically connected to a core wire 2a of the shielded cable 2. The external conductor terminal 3c has a contact part 3e formed at its end, and the base part is secured to and electrically connected to an external conductor 2b of the shielded cable 2.
The non-shielded terminal 5 to which the non-shielded cable 4 is attached is similar to the core-wire terminal 3a for the shielded terminal 3, and has a contact part 5a. 
The shielded terminal 3 and the non-shielded terminal 5 are respectively inserted into a shielded-terminal insertion hole 6 and a non-shielded-terminal insertion hole 7 in the terminal housing 1. The terminal housing 1 has an engaging piece 8 at the top thereof, and the engaging piece 8 has an engaging projection part 8a. 
A connector housing 11 includes a terminal mounting hole 12 and lead-out terminals 13, 14, and 15. The lead-out terminals 13 and 15 have a bar shape and project into the terminal mounting hole 12 from the back of the connector housing 11. The lead-out terminal 14 has a plate shape and is disposed along the inner face of back of the terminal mounting hole 12. The lead-out terminal 14 has a hole 14a which lets the lead-out terminal 13 pass through it without being in contact with it, and the back face is connected to a lead 14b. The connector housing 11 has an engaging hole 16 at the top thereof, and an engaging indentation 16a is formed in the engaging hole 16.
The terminal housing 1 is inserted into the terminal mounting hole 12 of the connector housing 11. The engaging piece 8 of the terminal housing 1 is inserted into the engaging hole 16 of the connector housing 11, and the engaging projection part 8a of the engaging piece 8 is engaged with the engaging indentation 16a in the engaging hole 16. The lead-out terminal 13 of the connector housing 11 comes into contact with the contact part 3d of the core-wire terminal 3a in the terminal housing 1, and the lead-out terminal 14 is held in contact with the contact part 3e of the external conductor terminal 3c. The lead-out terminal 15 is held in contact with the contact part 5a of the non-shielded terminal 5.
The connector illustrated in FIGS. 1A and 1B serves both the shielded cable 2 and the non-shielded cable 4 as described above and allows both the shielded cable 2 and the non-shielded cable 4 to be attached or detached as an integrated unit.
In the terminal housing 1, the core-wire terminal 3a connected with the core wire 2a of the shielded cable 2 is surrounded and shielded by the external conductor terminal 3c. While the terminal housing 1 is inserted into the connector housing 11, a part projecting into the terminal mounting hole 12, of the lead-out terminal 13 of the connector housing 11 in contact with the core-wire terminal 3a, is also surrounded by the external conductor terminal 3c and is therefore shielded. However, a part of the lead-out terminal 13, including an L-shaped part projecting from the back of the connector housing 11, is not shielded at all, causing impedance mismatching. If a high-speed (high-frequency) signal is transmitted, deterioration of the transmission characteristics is unavoidable.